委托的使用场景
举一个整数冒泡排序的例子:/// <summary> /// 整数排序 /// </summary> class SortInt { /// <summary> /// 比较大小 /// </summary> /// <param name="i1"></param> /// <param name="i2"></param> /// <returns></returns> public bool compare(int i1, int i2) { if (i1 > i2) { return true; } else { return false; } } /// <summary> /// 排序 /// </summary> /// <param name="tosort"></param> public void sort(int[] tosort) { for (int i = 0; i < tosort.Length; i++) { for (int j = 0; j < tosort.Length - (i + 1); j++) { if (compare(tosort, tosort)) { int temp = tosort; tosort = tosort; tosort = temp; } } } } }class Program { static void Main(string[] args) { int[] tosortint = new int[] { 8, 7, 6, 5 }; SortInt si = new SortInt(); si.sort(tosortint); for (int i = 0; i < tosortint.Length; i++) { Console.WriteLine(tosortint); } } }
然后再举一个职员薪水冒泡排序的例子
/// <summary> /// 职员 /// </summary> class Employee { private int id; private string name; private double salary; public Employee(int id, string name, double salary) { this.id = id; this.name = name; this.salary = salary; } public int ID { get { return id; } set { id = value; } } public string Name { get { return name; } set { name = value; } } public double Salary { get { return salary; } set { salary = value; } } } /// <summary> /// 职员薪水排序 /// </summary> class SortEmployee { public bool compare(Employee e1, Employee e2) { if (e1.Salary > e2.Salary) { return true; } else { return false; } } public void sortEmployee(Employee[] tosort) { for (int i = 0; i < tosort.Length; i++) { for (int j = 0; j < tosort.Length - (i + 1); j++) { if (compare(tosort, tosort)) { Employee e = tosort; tosort = tosort; tosort = e; } } } } }class Program { static void Main(string[] args) { Employee[] tosortemployee = new Employee[] { new Employee(2, "zh", 600), new Employee(1, "pm", 200) }; SortEmployee se = new SortEmployee(); se.sortEmployee(tosortemployee); for (int i = 0; i < tosortemployee.Length; i++) { Console.WriteLine(tosortemployee.Salary); } } }
这两个例子
相同之处:排序算法相同
不同之处:比较对象不同/比较算法不同
为了实现代码重用,体现oop思想,我们进行如下重构:
class Program { static void Main(string[] args) { object[] tosortint = new object[] { 8, 7, 6, 5 }; SortInt si = new SortInt(); SortDel sd = new SortDel(si.compare); Sort s = new Sort(); s.sort(tosortint, sd); for (int i = 0; i < tosortint.Length; i++) { Console.WriteLine(tosortint); } Console.WriteLine("*******************************************************"); object[] tosortemployee = new object[] { new Employee(2, "zh", 600), new Employee(1, "pm", 200) }; SortEmployee se = new SortEmployee(); sd = new SortDel(se.compare); s = new Sort(); s.sort(tosortemployee, sd); for (int i = 0; i < tosortemployee.Length; i++) { Console.WriteLine(((Employee)tosortemployee).Salary); } } } /// <summary> /// 整数比较 /// </summary> class SortInt { public bool compare(object o1, object o2) { int i1 = Convert.ToInt32(o1); int i2 = Convert.ToInt32(o2); if (i1 > i2) { return true; } else { return false; } } } /// <summary> /// 职员 /// </summary> class Employee { private int id; private string name; private double salary; public Employee(int id, string name, double salary) { this.id = id; this.name = name; this.salary = salary; } public int ID { get { return id; } set { id = value; } } public string Name { get { return name; } set { name = value; } } public double Salary { get { return salary; } set { salary = value; } } } /// <summary> /// 职员薪水比较 /// </summary> class SortEmployee { public bool compare(object o1, object o2) { Employee e1 = (Employee)o1; Employee e2 = (Employee)o2; if (e1.Salary > e2.Salary) { return true; } else { return false; } } } /// <summary> /// 比较代理 /// </summary> /// <param name="o1"></param> /// <param name="o2"></param> /// <returns></returns> public delegate bool SortDel(object o1, object o2); /// <summary> /// 通用排序 /// </summary> class Sort { public void sort(object[] tosort, SortDel sd) { for (int i = 0; i < tosort.Length; i++) { for (int j = 0; j < tosort.Length - (i + 1); j++) { if (sd(tosort, tosort)) { object e = tosort; tosort = tosort; tosort = e; } } } } }
重构?
在此引入了SortDel代理,用来进行比较两个对象,在进行整数类冒泡排序时此代理指向整数类的比较方法,而在进行自定义职员类的冒泡排序时指向自定义职员类的比较方法,从而使冒泡排序算法被抽象出来,成为一个通用的方法.今后再需要进行学生单科成绩/学生综合成绩的冒泡排序时,只需添加一个学生类,再提供一个单科成绩比较的方法和一个综合成绩比较的方法,就可以了,不需再把冒泡排序的算法再写一遍,实现了代码的重用,体现了OOP.
页:
[1]